1. Technical Field
The present invention relates to a printing device and a roll diameter calculating method and program.
2. Related Art
Among printing devices, for example ink jet printers, there is a type which uses a large-sized paper with a paper size of A2 or above. The ink jet printer using such a large-sized paper mainly uses a so-called roll paper in addition to a cut paper. In addition, hereinafter, a so-called roll paper obtained by winding-up a paper is called a roll body, and a portion drawn out from the roll body is called a paper.
The paper is drawn out from the roll body by rotating a feeding roller by means of a paper feeding motor (a PF motor).
In addition, there is proposed a printer in which a motor (a roll motor) for rotating a roll body is provided to operate two motors so that the tension of the paper is controlled between the roll body and the feeding roller (for example, see JP-A-2009-263044).
As a paper is drawn out from the roll body, the diameter and weight of the roll body vary. Along with the variation of the diameter and weight of the roll body, the tension of the paper between the roll body and the feeding roller pair rotated by the PF motor greatly fluctuates. In other words, in order to improve precision of the tension control, it is necessary to correctly check the diameter of the roll body.